In the past, it is well known such a washing machine in which a bottomed cylindrical washing tank is supported inside a box-shaped main body and a disc-shaped rotary wing named as a pulsator is arranged at the bottom of the washing tank (for example, referring to the Patent Literature 1).
A rotary shaft is arranged at the center of the rotary wing, and a plurality of stirring blades centered on the rotary shaft and extending radially are formed on the surface of the rotary wing. Moreover, the rotary blades can rotate by a driving unit including a motor to stir water and washing objects put in the washing tank, so as to wash the washing objects.